Detachable sideshade for spectacles

ABSTRACT

A sideshade for reducing peripheral glare that is removably attachable to a temple of spectacles such that the wearer of the spectacles is not required to remove the spectacles in order to attach the sideshade to or detach the sideshade from the temple of the spectacles. The detachable sideshade is optical or near-optical quality so as not to degrade the wearer&#39;s peripheral vision. The sideshade may be light in weight and easy to attach and remove.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a continuation-in-part ofU.S. application Ser. No. 11/421,355, filed May 31, 2006, to issue asU.S. Pat. No. 7,328,998 on Feb. 12, 2008, which is incorporated hereinby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a detachable sideshade forspectacles, and more particularly concerns a sideshade that is removablyattachable to a temple of spectacles such that the wearer of thespectacles is not required to remove the spectacles in order to attachthe sideshade to or detach the sideshade from the temple of thespectacles. The detachable sideshade is optical or near-optical qualitysuch that the sideshade does not degrade or distort details in theperipheral viewing area of the wearer and may be tinted for reducingperipheral glare.

2. Prior Art

In the field of optical wear, a wide variety of sunglasses and goggleshave been developed over the years for various purposes, depending uponthe specific function of the sunglasses or the activity involved whilewearing the sunglasses. Optical wear has been created to reduce glarefrom point sources of light, such as from oncoming cars or from directsunlight. Optical wear has also been created to reduce the glare frombroad regions of high illumination, such as office lighting, sky glare,and ground glare. Optical wear also has been developed for directingsight into specific fields of vision. This type of eyewear enables theviewer to assume a correct posture or position for carrying out aphysical activity; the great majority of the prior art in thisapplication has been in developing golfing glasses. Finally, opticalwear has been designed to reduce visual stress in contrasting lightingsituations and to enhance feature extraction in different fields ofvision, these types of optical wear can be useful during physicalactivities where it is desirable to see a specific object against abackground, such as golfing, fishing, hunting or other outdoorrecreational activities.

One area that prior art has not addressed is the situation encounteredby pilots of jet aircraft, which are flown typically at altitudesbetween 35,000 and 45,000 feet. At these heights during the day, theillumination from outside the cockpit is especially high. The highillumination comes from scattered light from both the sky and clouds.Indeed, when flying over clouds, pilots typically experienceillumination values around 9,000 lux even when they are not looking inthe direction of the sun. By contrast, under these external lightingconditions, the illumination of the instrument panel can be typicallyaround 30 lux. In this case, the ratio between the outside illuminationto that of the instrument panel is 300 to 1. Making transitions betweenthese two contrasting fields of illumination can be stressful to theeyes.

Of the variations of sunglasses disclosed in prior art, none hassatisfactorily solved the problem of balancing the illumination betweenoutside and inside the cockpit—a problem that pilots flying at altitudeencounter. Ordinary dark sunglasses do not solve this problem; whilethey do reduce the outside illumination to a comfortable level for thepilot, they can render the instrument panel too dark for the pilot todiscern readings on the gauges. On the other hand, vignetted sunglasslenses assist in the overall balancing of illumination outside thecockpit with that of the instrument panel, but they permit too muchlight to enter a pilot's eyes, thus causing glare when the pilot viewsthe instruments.

The limitations of prior art described above highlight the need forsunglasses that specifically address the two and often related problemsthat many jet pilots routinely encounter when flying at altitude: thatis, (1) the contrast in illumination causes stress on the pilot's eyesresulting from the eyes having to adjust back and forth between the highillumination from outside the cockpit and the low illumination from theinstrument panel; and (2) the glare caused by the high illumination candegrade the ability of the pilot to adequately see the instruments.Moreover, these two problems are exacerbated as the pilot ages.

To fully understand the problem the specially tinted lens solve, it ishelpful to define the difference between the horizon and the horizontalplane in which the aircraft is flying. The horizon is plane tangent tothe earth's surface at an observer's position and the horizontal planeis perpendicular to the vertical axis to the earth. Between 35,000 ftand 45,000 ft the horizon is approximately 3.3° to 3.8° below thehorizontal plane. Consequently, whenever the aircraft is above a uniformlayer of cloud that extends to the horizon, the illumination from thatcloud layer originates from below the horizontal plane.

The illumination that a pilot experiences when flying at these highaltitudes can be significantly different from that experienced by aperson on the ground. For example, when pilots fly above the clouds, theillumination experienced when they look horizontally and below istypically greater then when they look above the horizontal plane. Thishigh illumination at and below the horizontal plane poses a uniqueproblem for pilots when they look at the instruments, in that the highillumination from outside the cockpit can be relatively close to theirintermediate field of vision of the instruments. The reverse tends to bethe case for a person on the ground, where the illumination generallyincreases when looking upwards.

The specially tinted lens, when adapted to sunglasses, enable a pilot toeasily view outside the cockpit into high illumination andsimultaneously view the instrument panel in low illumination without theeyes having to compensate for the previously described problems ofadjustment and glare. The specially tinted lens reduces visual stress tothe eyes by greatly reducing the difference in illumination as receivedby the eyes between lighting outside the cockpit and the instrumentpanel. In addition, this reduction in light received by the eyes fromoutside the cockpit greatly reduces glare that can impair the pilot'svision of the instrument panel.

The specially tinted lens addresses the specific and unique conditionpresent in the cockpit of a jet aircraft where the instrument panel andnose of the aircraft block the high illumination from outside thecockpit from entering the intermediate section of the lens.

Under some situations, disability glare can be so great from theillumination outside the cockpit that details of the instruments cannotbe read without blocking or greatly attenuating the outsideillumination. The specially tinted lens greatly reduce glare experiencedby pilots and effectively eliminate disability glare by attenuating thehigh illumination that enters through the front of the sunglasses.However, even when wearing these sunglasses with the specially tintedlenses, there still can be high illumination that enters the pilot'seyes from the sides of the spectacle frames, causing what is calleddiscomfort glare. Discomfort glare does not inhibit the pilot fromreading details on the instrument panel, but it creates an uncomfortableand/or distracting viewing situation. This discomfort glare can bemitigated by use of sideshades with sunglasses with the specially tintedlenses. A reference to disability and discomfort glare is given in theIntroduction to Visual Optics, Alan H. Tunnacliffe 4^(th) Edition 1993.Association of British Opticians, Canterbury, ISBN 0-900099-28-3, 603pages.

The detachable sideshades disclosed herein are novel in that they can beinstalled and removed without the pilot having to remove his or hersunglasses or headset, thus creating a minimum amount of distraction forthe pilot. Moreover, either or both sideshades can be worn as thelighting situation requires. A pilot, for instance, may wear just onesideshade—the sideshade that faces the outside of the cockpit. Thedetachable sideshades may be optical or near-optical in quality and willenable the pilot to maintain peripheral vision. The optical density ofthe sideshades may be such that the light transmitted through them willbe approximately the same as that transmitted through the distantportion of the specially tinted lenses.

In the field of eyewear concerned with the peripheral area of one'svision, there are numerous known devices, such as sideshades,sideshields, side guards, etc. Sideshades reduce the peripheralillumination to a comfortable level, which tends to enhance one's visionin the forward direction. Sideshields have the primary purpose ofprotecting the eyes, generally from flying objects. Sideshields can alsoprotect one's eyes from wind and high intensity illumination, such aslaser light. In addition, sideshields can also function as sideshades.

In the field of sideshades and sideshields for spectacles, there is awide range of prior disclosed art that primarily addresses the need toprotect the eyes of the spectacle wearer from injury from flyingobjects, high illumination or dangerous radiation. In general, earlierprior art has disclosed sideshields that are non-optical quality andrigid and that require the wearer to remove his or her spectacles toeither install or remove the sideshields. Installation and removal ofthe sideshields disclosed in the prior art are tedious, and therefore,the wearer would have to remove his or her spectacles to install orremove these sideshields. The detachable sideshades disclosed herein maybe optical or near-optical in quality, are light, can be flexible and donot require the wearer to remove his or her spectacles when installingor removing them.

Sideshields that meet impact resistance standards (e.g., AmericanNational Standard Institute, ANSI, Z87.1) must be securely mounted ontothe eyewear in question, and therefore, do not lend themselves to beinginstalled or removed while an individual is wearing his or her eyewear.Universal sideshields that fit a broad range of frame shapes and sizesare typically more labor intensive to install and remove thansideshields that are frame type and size specific. Sideshields that fallinto this category include those of Simmons (U.S. Pat. Nos. 5,748,278,6,393,609, 6,832,389, and 7,013,495). These sideshields are not opticalquality nor are they easily installed or removed.

It is therefore desirable to provide a detachable sideshade that iseasily installed or removed from the frame of sunglasses.

It is therefore further desirable to provide a detachable sideshade thatmay easily installed or removed while an individual is wearing his orher eyewear.

It is yet further desirable to provide a detachable sideshade of opticalor near-optical quality as to not distort or degrade a wearer'speripheral vision.

It is yet further desirable to provide a detachable sideshade that istintable.

It is yet further desirable to provide a detachable sideshade beingtransparently tintable to reduce glare caused from the high illuminationin a wearer's peripheral vision.

It is yet further desirable to provide a detachable sideshade thatconforms to the outside of the spectacle frame to prevent light fromentering the wearer's eyes from the region between the sideshade and theeyewear frame.

It is yet further desirable to provide a detachable sideshade thatvertically extends above and below the temple and conforms to thewearer's head to prevent light from entering the wearer's eyes fromareas above and below the temple.

SUMMARY OF THE INVENTION

In general, in a first aspect, the invention relates to a detachablesideshade removably securable to a temple of spectacles such that awearer is not required to remove the spectacles in order to attach thesideshade to or detach the sideshade from the temple of the spectacles.The detachable sideshade is optical or near-optical quality such thatthe sideshade does not degrade or distort details in the peripheralviewing area of the wearer.

The detachable sideshade may be constructed of a thin, flexible film orplastic. The film sideshade may have a thickness between 100 and 200 μm,while the plastic sideshade may have a thickness between 150 and 300 μm.The sideshade may be unitary in construction or a two-part sideshade.The sideshade may be constructed of a rigid or semi-rigid plastic havinga thickness between 250 and 1000 μm.

The sideshade may include a tapered channel for receipt of the temple ofthe spectacles. The channel can include a cylindrical section. Thedetachable sideshade may include a clasp mechanism to removably securethe sideshade to the spectacles. The clasp mechanism may include atensioning spring, a pair of tabs capable of movement to selectivelytension the spring and clasps that are releasably securable to thetemple of the spectacles. The clasp mechanism may include at least onelever capable of movement, a spiral shaft having at least one movableclasp and at least one stationary clasp attached, and a compressionspring that forces the lever into a closed position. The movement of thelever causes the spiral shaft to rotate resulting in the moveable claspmoving close to or away from the temple of the spectacles.

The detachable sideshade may also include a cutout area near a frontportion. The detachable sideshade may include an overturned area near afront portion that is generally arcuate to conform to the frame of thespectacles.

The sideshade may include tinting having a neutral filter categorynumber range between 2 and 6 (transmittance between 25% and 1.56%). Thesideshade also include vignetted tinting, either in the vertical orhorizontal direction, a color tinting, photochromic, polarization, UVprotection, or a combination thereof.

The spectacles may include specially tinted lenses having at least twodistinct, contrasting tintings between at least three fields of vision:a far field of vision tinted sufficient to prevent the high illuminationfrom entering a pilot's eyes; an intermediate field of vision tinted toenable the pilot to easily see a dimly illuminated instrument panel; anda near field of vision tinted to enable the pilot to easily view mapsand other information.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an example of a pair of sunglasses withspecially tinted lenses suitable for wearing while flying an airplane inaccordance with an illustrative embodiment of the special-purposesunglasses disclosed herein;

FIG. 2 is a perspective view of an example of a tri-tinted lens inaccordance with an illustrative embodiment of the special-purposesunglasses disclosed herein;

FIG. 3 is a cross-sectional view of an example of an aircraft cockpitshowing the approximate location where one of the pilots sits and thediffering levels of illuminations from the high ambient light outsidethe cockpit to the low level of illumination from the instrument panel;

FIG. 4 is a schematic view of the tinting density of the tri-tintedlenses within a system of Cartesian coordinates having in the abscissa(X-axis) the filter category number of the tinting and in the ordinate(Y-axis) the vertical distance from the center of the lens as depictedin FIG. 2;

FIG. 5 is an outside perspective view of an example of a pair ofsunglasses with a detachable sideshade attached in accordance with anillustrative embodiment of the detachable sideshade disclosed herein;

FIG. 6 is an inside perspective view of the pair of sunglasses with thedetachable sideshade attached in accordance with the illustrativeembodiment of FIG. 5;

FIG. 7 is a top elevation view of the pair of sunglasses with thedetachable sideshade attached in accordance with the illustrativeembodiment of FIG. 5;

FIG. 7A is a cross-sectional view along line A-A of the detachablesideshade shown in FIG. 7;

FIG. 7B is a cross-sectional view along line B-B of the detachablesideshade shown in FIG. 7;

FIG. 7C is a cross-sectional view along line C-C of the detachablesideshade shown in FIG. 7;

FIG. 8A is an outside perspective view of an example of a detachablesideshade in accordance with another illustrative embodiment of thedetachable sideshade disclosed herein;

FIG. 8B is an outside perspective view of the detachable sideshade ofFIG. 8A in the open position;

FIG. 8C is an inside perspective view of the detachable sideshade ofFIG. 8B;

FIG. 9 is an inside perspective view of the detachable sideshade of FIG.8A attached to sunglasses;

FIG. 10A is a side perspective view of an example of a detachablesideshade in accordance with another illustrative embodiment of thedetachable sideshade disclosed herein; and

FIG. 10B is an end perspective view of the detachable sideshade of FIG.9A.

Other advantages and features will be apparent from the followingdescription, and from the claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The devices discussed herein are merely illustrative of specific mannersin which to make and use this invention and are not to be interpreted aslimiting in scope.

While the devices have been described with a certain degree ofparticularity, it is to be noted that many modifications may be made inthe details of the construction and the arrangement of the devices andcomponents without departing from the spirit and scope of thisdisclosure. It is understood that the devices are not limited to theembodiments set forth herein for purposes of exemplification.

Under the specially tinted lenses for use in flying airplanes, the farfield of vision has medium to exceptionally dark tinting (Filtercategory between 2 and 6) to reduce the light from a sunlit sky, oversunlit cloud tops, or in clouds. This enables an aircraft pilot toeasily see out of the cockpit into highly illuminated environments. Theintermediate field of vision is essentially clear (Filter category 0) toenable the pilot to easily see a dimly illuminated instrument panel ascompared to the high illumination outside that aircraft. The near fieldof vision may have a range of tinting from clear (Filter category 0) tomedium (Filter category 3) for reading maps, etc. In addition, thechange in tinting is discontinuous (i.e., sharp) from one field ofvision to another. The specially tinted lenses work because the aircraftstructure (i.e., nose and instrument panel) substantially blocks outsidelight from coming into the intermediate field of vision where the lensis clear.

The density of the tinting on the lenses is based on the EuropeanStandard EN1836:1997. Under this standard, the density of the tinting ofthe sunglasses is numerically categorized as given in the followingtable:

Filter Calculated Approximate Density of Brightness CategoryTransmittance Transmittance Tinting on of Number (N) (T) Range On LensesEnvironment 0 100.% 80% to 100% Clear or Dim very light 1  50.% 43% to80% Light Normal 2  25.% 18% to 43% Medium Normal 3 12.5% 8% to 18% DarkHigh 4 6.25% 3% to 8% Very Dark Exception- ally High

The calculated transmittance (T) is the percentage of visible light thatis transmitted through the lens as compared to the incident light ontothe lens. T is related to the filter category number (N) as given in thefollowing equation:

$\begin{matrix}{T = {\left( \frac{1}{2} \right)^{N} \cdot 100}} & \left( {{Equation}\mspace{14mu} 1} \right)\end{matrix}$

The concept of the filter category is extended for values of N of 5 and6 having a calculated transmittances of 3.13% and 1.56%, respectivelyand represent exceptionally dark tinting. The use of filter categorynumbers (N) to describe the tinting of sunglasses is practical becausethe eye can sense change in filter density for one category number tothe next. However, N is not restricted to integer values when relatingit to transmittance values 1.

The specially tinted lenses are application-specific; that is, onecannot expect sunglasses made with these specially tinted lenses to besuitable for general use. The specially tinted lenses work properly onlyin an aircraft cockpit or other such environment where a barriersubstantially blocks the high ambient illumination from the intermediateand near viewing areas on the lens.

The tinting density and the pattern of the different tinting areas onthe specially tinted lenses may be custom made for the specific aircrafttype because of the variations in shapes of the instrument panels andglare shields. The pattern of tinting may need to be customizeddepending on which seat the pilot may be sitting. Lastly, the densityand type of tinting may need to be optimized for a pilot flying intropical, temperate regions, or sub-arctic regions.

Observations in the sub-arctic region indicate particularly highcontrasting viewing conditions at altitude between outside the cockpitand the instrument panel. In this region, cloud tops are typically lowerthan found in temperate or tropical regions and thus jet aircraft aretypically more frequently above cloud tops in the sub-arctic than intemperate or tropical regions. In addition, lower sun angles withrespect to the horizon in the sub-arctic as compared to the temperate ortropical regions probably produce less illumination coming into to thecockpit from above the horizontal plane which illuminates the interiorof the cockpit, including the instrument panel. This puts the pilot in aviewing situation where the horizon can be brilliantly lit but theinstrument panel is dimly lit.

The specially tinted lenses are not limited to being mounted in justordinary spectacles or sunglasses. The lenses can be mounted in “clipon” sunglasses, mounted in goggles wherein the goggles can have a singlelens with tinting applied in front of the eyes, or the tintings can beapplied to a visor that typically is part of a helmet used for flying.

The tri-tinting on the lenses is considered to be of neutral density.However, color tintings that are typically used in aviator's sunglass,e.g., green, brown, and yellow, can be used. There is a discontinuity,or sharp contrast, between at least two of the viewing areas on thelens.

Vignetted tinting may also be used for the far field of viewing. Inaddition, the vignetted tinting on the sunglasses can have a gradient inthe tinting opposite to that used on ordinary sunglasses. That is, thetinting can start off light at the top of the lens and increase indensity towards the center of the lens. This would tend to block thehigh intensity of light coming from clouds below the horizontal planewhen a pilot is viewing outside the cockpit.

The specially tinted lenses could be photochromic, have UV protection,could be impact resistant or could be polarized. In addition, thespecially tinted lenses may be with or without correction (ophthalmiclenses) in any one or all of the fields of vision.

Referring to the figures of the drawings, wherein like numerals ofreference designate like elements throughout the several views, andinitially to FIG. 1, specially tinted lenses for use in flyingairplanes. Sunglasses 10 can be of any conventional design, comprisingtwo lenses 20 mounted to a frame 12, to which two temples 14 arehingedly attached. Frame 12 can be of any design, but usually includes anose piece 14 and/or bridge 16 that supports frame 12 on the wearer'sface. Lenses 20 are tri-tinted for the different fields of vision. A farfield of vision area 22 (large dark grey portion) has dark tinting,intermediate field of vision area 24 (horizontal clear portion) has notinting, and near field of vision area 26 (small semi-circle portion)has light to medium tinting. The tinted fields of the lenses can be ofany shape and can run predominantly horizontally, vertically or in anydirection to best reduce the bright light and selectively allow dimlight to reach the viewer's eyes.

FIG. 2 illustrates lenses 20 as tri-tinted in order to reduce glare forthe wearer when viewing in the near or intermediate field of vision fromhigh illumination for the far field of vision. Lenses 20 may be used ineither spectacles or sunglasses. Lenses 20 can be without power, i.e.,non-prescription lenses, or a prescription lens with power in one ormore of the three viewing zones.

Lenses 20 may have three different areas to enable the wearer to see inthree fields of vision, a far field (V_(f)) 22 (typically where the eyesfocus at infinity), an intermediate field of vision (V_(i)) 24 (wherethe eyes focuses at 32 inches (0.81 m)) and a near field of vision(V_(n)) 26 for reading (where the eyes focuses at 16 inches (0.41 m)).These distances are set forth in the Federal Aviation Agencies (FAA)standards required of a First Class Medical. 14 C.F.R. §67.103. In theparticular embodiment, V_(f) 22 is tinted with approximately a filtercategory value of 4 (N_(f)˜4), V_(i) 24 with N_(i)˜0 and V_(c) 26 withN_(c)˜2. The line XX passes through the center of the far field of viewarea on lens 20. As can be seen in FIG. 2, the dark tint may extendbelow line XX approximately 2.5 mm at which point the lens transitionsto the area for intermediate viewing and the lens is clear. The line ZZpasses though the centers of the intermediate 24 and near 26 fields ofvision. The distance along ZZ is plotted as the ordinate (Y-axis) inFIG. 4 below.

Lenses 20 may have three distinct densities of tint. The tintings can beexpressed as the transmittance through the lens or as filter categoryvalues. The tinting densities may be applied in general to the threefields of vision as described above. For far field viewing 22, the lensmay have dark tinting, for example, a filter category number between 2and 6 (transmittance between 25% and 1.56%). For intermediate fieldviewing 24, a filter category number may be zero, i.e., no tinting(transmittance of 100%). For near field viewing 26, a filter categoryvalue between 1 and 3 be used (transmittance between 50% and 12.5%).

The range of filter category values and transmittances are quantified inthe following table for the neutral density tinting:

Lens Viewing Filter Category Area Number Transmittance V_(f) 2 ≦ N_(f) ≦6 25% ≧ T_(f) ≧ 1.56% V_(i) 0 ≦ N_(i) ≦ N_(f) − 1 100% ≧ T_(i) ≧ 2 ·T_(f) V_(n) N_(i) ≦ N_(n) ≦ N_(f) T_(i) ≧ T_(n) ≧ T_(f)where:

-   N_(f) is the filter category number of the tinting in the far field    of viewing area on the lens (V_(f)),-   N_(i) is the filter category number of the tinting in the    intermediate field of viewing area on the lens (V_(i)),-   N_(n) is the filter category number of the tinting in the near field    of viewing area on the lens (V_(n))-   T_(f) is the transmittance of the tinting in V_(f),-   T_(i) is the transmittance of the tinting in V_(i),-   T_(n) is the transmittance of the tinting in V_(n).

It is envisioned that a pilot will initially evaluate a pair of thesespecial purposes sunglasses having initial tintings as follows; N_(f)=4,N_(i)=0, N_(n)=2. Pilots can have the tintings changed as required fortheir situations.

On the ophthalmic trifocal, the tinting for distant viewing can coversome of the area on the intermediate portion of the lens so as toprevent high illumination from outside the cockpit from interfering withthe pilot's viewing of the instrument panel. That is, for a typicaltrifocal lens the intermediate distant area on the lens may be largerthan what is required to adequately view the instrument panel.

Light sources of excessive brightness or uneven distribution in thefield of view can cause glare, which may in turn cause a mild sensationof discomfort or an intolerable feeling of pain. The physiologicalorigins of this discomfort has been extensively studied and discussed bythose skilled in the art. To reduce glare, it is imperative that highintensity illumination from outside the cockpit be substantially reducedbefore it reaches the pilot's eyes. For example, those skilled in theart recognize that the intensity of a glare source can be quantified.

U.S. Pat. No. 4,338,003 granted to Adrian describes an equation thatrelates the glare experienced to the intensity of the illumination thatcauses the glare. This formula takes into account the viewer's age as afactor of the glare illumination, and is referred to as “equivalentstray-light illumination:”

$\begin{matrix}{L_{saq} = \frac{K \cdot E_{B\; 1}}{\theta^{2}}} & \left( {{Equation}\mspace{14mu} 2} \right)\end{matrix}$where L_(saq) is intensity of the glare in candles/meter² (cd/m²); K isan age-dependent constant approximately 10 for the age group between 20and 30, E_(B1) is the illumination in lux (lx) produced by the source ofglare in the plane of the eye normal to the direction of viewing, and θis the angle between the viewed object and the centre of the source ofglare in degrees.

The equivalent illumination in lux of the glare can be estimated fromthe intensity of the glare (L_(saq)) as follows:

$\begin{matrix}{E_{saq} = \frac{L_{saq}}{4 \cdot \pi}} & \left( {{Equation}\mspace{14mu} 3} \right)\end{matrix}$

As stated above, the average illumination entering the cockpit of anairplane through the windshield can typically be 9,000 lux. The anglebetween the upper part of the instrument panel and the lower part of thewindshield is approximately 12°. Applying these values to Equation 2,the intensity of the glare in the cockpit is approximately 625 cd/m²,which results in an approximate equivalent illumination of 50 lux to thepilot's eyes (Equation 3). This indicates that the glare a pilot canexperience while viewing the instruments can easily be of the order ofthe illumination of the instruments themselves.

The example above using Equation 2 to estimate the equivalentstray-light illumination is conservative if not underestimated by afactor of 10 because the illumination from outside the cockpit thatstrikes the pilot's eye was not integrated over the entire viewingscene. From practical experience in the sub-artic the glare can be sointense it is like viewing the instruments through a translucent vale.

FIG. 3 shows a cross-sectional view of jet aircraft cockpit 30 showingthe location where the pilot is seated 32. The pilot 32 typically isrequired to view outside the aircraft 34, the instrument panel (36 and42) and paper or an electronic display on what is frequently called theapproach plate holder 38. The pilot 32 frequently has to look back andforth between these three viewing scenes 34, 36 and 38 in rapidsuccession. The high illumination from outside the cockpit and below thehorizontal plane 34 when combined with the small angle 40 formed fromthe upper part of the instrument panel 42, the pilot's eyes 44 and thelower portion of the airplane's windscreen 46 is a major contributor tothe high level of glare experienced by pilots (Equations 2 and 3).

One of the starkest lighting situations between the outside illumination34 and the lighting from of the instrument panel 50 commonly occurs whenflying above a relatively uniform cloud deck with a clear sky above. Inthis situation, the highest illumination 34 is coming from below thehorizontal plane 52. Also in this situation, there can be relativelylittle direct outside light illuminating the instrument panel (36 and42). In this case, the illumination from outside the cockpit and belowthe horizontal plane 52 can be more than 100 times greater than theillumination from the instrument panel (36 and 42).

Under the above lighting situation, if the pilot is wearing sunglasseswith sufficiently dark uniform tinting to make viewing outside thecockpit 34 comfortable, viewing the instrument panel (36 and 42) can bedifficult because the instruments appear too dark. If the pilot iswearing vignetted sunglasses, high illumination can be admitted to thepilot's eyes from just above the instrument panel 46 from outside thecockpit, which may not help reduce the contrast between the illuminationfrom outside the cockpit 34 and the illumination from the instruments50. In addition, the high illumination from outside the cockpit 34admitted to the pilot's eyes can cause unacceptable glare, which rendersthe instruments hard to read. The severity of the glare is caused inpart because of the small angle 40 between the outside illumination 34and the illumination from the instrument panel 50.

Observations indicate that the illumination from the approach plateholder 54 is usually noticeable brighter than the illumination from theinstrument panel (36 and 42). Thus, the pilot is frequently faced withhaving to view three drastically different illuminated screens.

FIG. 4 shows the density of the tinting as a function of the distancefrom the center of the lens. The ordinate (Y-axis) is the distance alongline ZZ in FIG. 2. There is a discontinuous change in the tintingdensity between the three fields of vision for the different viewingdistances as delineated in FIG. 2 above. On FIG. 4, 62 is the tinting inthe far field of vision in FIG. 2 (22), 64 is the clear area in FIG. 2(24) and 66 is the tinting on the area on the lens for near viewing.Lastly 68 is the discontinuous transition from the area on the lens fornear viewing (FIG. 2, 26) back to the area on the lens for distantviewing (FIG. 2, 22). This lower part of the lens (FIG. 2, 22) is notintended for viewing distant objects but the dark tinting will preventhigh illumination for coming into the pilot's eyes especially if thepilot has the need to look vertically at an overhead panel.

The specially tinted lenses mitigate disability glare; however, undersome lighting conditions, there can be high ambient light that entersbehind and from the sides of sunglasses with the specially tintedlenses, which can cause discomfort glare.

To further reduce glare and improve the pilot's viewing of theinstrument panel these special-purpose sunglasses or, in fact, anyordinary sunglasses, can include the detachable sideshades. Thedetachable sideshade is optical or near-optical quality so as not todegrade the wearer's peripheral vision. The detachable sideshade canvary in rigidity from film material to thicker molded plastic with adesign objective to be light in weight and easy to attach and remove.For example, the detachable sideshade may be a unitary piece of filmthat is held in place on the temple of the eyewear by the elasticity ofthe material. The detachable sideshade may also be a two-part sideshadeformed on the concept of a spring hinge. The hinge is spring-loaded toclasp the temple of the eyewear. The sideshade is removed by opening theclasps against the tension of the spring. Further, the detachablesideshade may be a unitary piece of plastic or a two-part sideshade thathas a clasp mechanism. The clasp is removably secured to the temple. Theclasp is opened by moving a lever on the sideshade. The mechanismtransforms longitudinal movement of the lever into rotational movementof the clasps.

FIG. 5 shows an outside perspective view of a detachable sideshade madefrom film or thin plastic. Sideshade (70) is shown attached to the lefttemple of a pair of aviator style sunglasses. Sideshades that are madefrom film or thin plastic are not intended as personal protectiveequipment (“PPE”) from flying objects, as specified by the AmericanNational Standard Institute in ANSI Z87.1 Standard. Also, these film orthin plastic sideshades are not intended for use in environments havingstrong winds because they could become dislodged and detached from theeyewear.

The sideshade (70) may be made of one piece of thermoplastic film orthin plastic. The thickness of the film can vary, for example, between100 and 200 μm. The thickness of the thin plastic may vary, for examplebetween 150 to 300 μm. Formed in the sideshade (70) is a tapered orattenuating channel (76). Towards the front of the sideshade (70), theremay be a cutout area and/or cavity (74) within the sideshade (70) toallow for the spectacle hinge. The front portion (78) of the sideshade(70) can have a small overturned area (82) that is essentiallyperpendicular to the temple (14) or main area of the sideshade (70) andin general arcuate in shape. This overturned area (82) is to preventun-attenuated light from entering between the spectacle frame and thesideshade and to give the sideshade more structure to maintain itsshape.

FIG. 6 shows an inside perspective view of the sideshades in FIG. 5. Atthe depth of the channel (76), the sideshade (70) is formed into asection that is cylindrical in shape. The tapered channel (76) receivesthe temple (14) and the cylindrical section of the sideshade (70) snapsonto the temple (14). The sideshade (70) is held into place by theelasticity of the film or plastic. This gives the sideshade (70) apositive and detachably secured mounting. Allowing the spectacle hingeto pass through the cavity (74) of the sideshade (70), or be enclosed bythe sideshade (70) permits the front portion (78) of the sideshade (70)to conform to the outside of the spectacle frame (80). The better theconformity of the sideshade (70) to the frame (80) the better thestability and security of the sideshade (70) is to the frame (80). Thefront portion (78) of the sideshade (70) may be arcuate to conform tothe spectacle frame (80); however, the sideshade (70) can be made toconform to any variety of spectacle frame shape, e.g. rectangular.

Longitudinal, i.e., fore and aft, movement of the sideshade isrestricted by the overturned area (82) of the front portion (78) of thesideshade (70) and by the cutout area (74) which houses the spectaclehinge. Rotation movement of the sideshade (70) is restricted by theconformity of the front portion (78) of the sideshade (70) with theoutside of the spectacle frame (80).

FIG. 7 is a top elevation view of sideshade (70) attached to thespectacle. FIGS. 7A, 7B and 7C show three cross-sectional views of thesideshade (70) at different locations along the temple (14) (A-A, B-B,and C-C). Towards the front of the sideshade (7A), the tapered channel(76) of the sideshade (70) nearly encloses the temple (14). Moving backalong the sideshade (7B), the tapered channel of the sideshade (70)encloses less of the temple (14). Towards the back of the sideshade(7C), the sideshade (70) is only tangent to the temple (14).

The sideshades (70) are not required to be symmetrical about the temple(14) of the sunglasses. The sideshades (70) allow conformity to thesides of the frame (80) of the eyewear and to accommodate for variationsin the angle between the temple (14) and frame (80) (pantoscopic angle).

FIGS. 8A, 8B, and 8C show a perspective view of a two-part sideshadewith a spring-hinge, capable of being detachably secured onto the temple(14) of the eyewear. The lower and upper parts of the sideshade areshown by (90) and (92). A spring (94) holds the sideshade (70) in asecured position on the temple (14) of the eyewear (FIG. 9). Extendingoutwards from the outside of the hinge are two tabs (96) and (98) inFIGS. 8A and 8B that face each other. When tabs (96) and (98) aresqueezed together against the tension of the spring (94), the clasps(100) and (102) open (FIG. 8C) and allow the sideshade (70) to beremoved from the temple (14). Towards the front portion (78) of thesideshade (70), there may be a cutout area and/or cavity (74) in boththe lower and upper parts (90) and (92) of the sideshade (70). Thecutout area (74) accommodates a hinge that attaches to the temple (14)of the frame (80) and allows the front portion (78) of the sideshade(70) to conform to the outside of the spectacle frame (80). The materialfor the two-part spring-hinge sideshade may be plastic with a thicknessbetween 250 and 1000 μm.

FIGS. 10A and 10B show the sideshade (70) made from a single piece ofplastic (110), which may be approximately 500 to 1000 μm in thickness.The sideshade (70) is detachably secured to the temple (14) of theeyewear by the clasping mechanism (116), which may be mounted onto orincorporated as part of the sideshade (70). The clasping mechanism (116)may be opened by moving a lever (112) in the forward direction whichopens the clasps (100) and (102) that holds the sideshade (70) onto thetemple (14). This lever (112) may be forced forward by the thumb whilethe index finger is supported by the overturned area (82) on the frontportion (14) of the sideshade (70). This clasp mechanism (116) convertslongitudinal movement of the lever (112) into rotational movement of aspiral shaft (114) to which half of the clasps (100) and (102) areattached (FIG. 10B). There may be a compression spring that forces thelever (112) back into the closed position to hold the clasps (100) and(102) securely on the temple (14).

The clasp mechanism (116) can be made of stationary clasps (100) and aclasps (102) that rotate. FIG. 10B shows a stationary clasp (100) and arotatable clasp (102). The rotatable clasp (102) may have two grips—oneat the front of a spiral rod (114) and one at the back of the spiral rod(114). Moving the lever (112) forward between 10 and 15 mm causes thespiral shaft (114) to rotate between 300 and 45°, thus moving the clasp(102) away from the temple (14). The cutout area (74) in the sideshade(70) accommodates the hinge of the spectacles, thus enabling thesideshade (70) to conform closely to the eyewear frame (80).

These sideshades are of optical or near-optical quality and may havemedium to exceptionally dark tinting (Filter category between 2 and 6).The tinting can be vignetted horizontally or vertically. The sideshades(70) are to be easily attached to the frame (80) of the sunglasses,without the sunglasses being removed. In addition, the sideshades are tobe compatible with headsets that a pilot typical wears. This will enablethe pilot to attach or remove the sideshades (70) with minimaldistraction while flying the airplane.

The tinting on the sideshades (70) may be neutral density, and the colortintings may be green, brown or yellow. Photochromic sideshades can beused in conjunction with fixed density tinting.

In addition to reducing glare, these sideshades (70) should improve awearer's peripheral vision.

Whereas, the devices have been described in relation to the drawings andclaims, it should be understood that other and further modifications,apart from those shown or suggested herein, may be made within thespirit and scope of this invention.

What is claimed is:
 1. A detachable sideshade, comprising: a detachablesideshade removably securable to a temple of spectacles such that awearer is not required to remove said spectacles in order to attach saidsideshade to or detach said sideshade from said temple of saidspectacles; and a clasp mechanism to removably secure said sideshade, tosaid spectacles, said clasp mechanism having a tensioning element, apair of tabs capable of movement to selectively tension said element,and clasps that releasably secure said sideshade to said temple of saidspectacles; wherein said sideshade is optical or near-optical qualitysuch that said sideshade does not degrade or distort details in theperipheral viewing area of said wearer.
 2. The detachable sideshade ofclaim 1 wherein said sideshade is constructed of a thin, flexible filmor plastic.
 3. The detachable sideshade of claim 1 wherein saidsideshade is unitary in construction.
 4. The detachable sideshade ofclaim 1 wherein said sideshade is a two-part sideshade.
 5. Thedetachable sideshade of claim 1 wherein said clasp tensioning element isa tensioning spring.
 6. The detachable sideshade of claim 1 wherein saidsideshade includes a cutout area near a front portion.
 7. The detachablesideshade of claim 1 wherein said sideshade includes an overturned areanear a front portion that is generally arcuate to conform to the frameof said spectacles.
 8. The detachable sideshade of claim 1 wherein saidsideshade is tinted having a filter transmittance between 100% and1.56%.
 9. The detachable sideshade of claim 1 wherein said sideshadeincludes vignetted tinting, either in the vertical or horizontaldirection, a color tinting, photochromic, polarization, UV protection,or a combination thereof.
 10. A detachable sideshade, comprising: adetachable sideshade removably securable to a temple of spectacles suchthat a wearer is not required to remove said spectacles in order toattach said sideshade to or detach said sideshade from said temple ofsaid spectacles; and a clasp mechanism to removably secure saidsideshade to said spectacles, said clasp mechanism having at least onelever and clasps, and wherein said clasp mechanism transformslongitudinal movement of said lever into rotational movement of saidclasps that releasably secure said sideshade to said temple of saidspectacles; wherein said sideshade is optical or near-optical qualitysuch that said sideshade does not degrade or distort details in theperipheral viewing area of said wearer.
 11. The detachable sideshade ofclaim 10 further comprising an overturned area near a front portion ofsaid sideshade that is generally arcuate to conform to the frame of saidspectacles.
 12. The detachable sideshade of claim 10 wherein said claspmechanism includes a spiral shaft having at least one movable clasp andat least one stationary clasp attached, and a compression spring thatforces said lever into a closed position; wherein movement of said levercauses said spiral shaft to rotate resulting in said moveable claspmoving close to or away from said temple of said spectacles.
 13. Thedetachable sideshade of claim 10 wherein said sideshade includes acutout area near a front portion.
 14. The detachable sideshade of claim10 wherein said sideshade includes vignetted tinting, either in thevertical or horizontal direction, a color tinting, photochromic,polarization, UV protection, or a combination thereof.
 15. Thedetachable sideshade of claim 10 wherein said sideshade is tinted havinga filter transmittance between 100% and 1.56%.